The present invention relates to a pouring device for dual-roll type continuous casting machines.
A conventional dual-roll type continuous casting machines comprises, as shown in FIG. 1, a pair of cooling rolls disposed in parallel with each other in a spaced-apart relationship as well as side dams 2 disposed at both end faces of the cooling rolls 1, whereby a basin 3 is defined into which a core 4 is partially submerged. Melt 6 such as molten steel in a tundish 5 above the core 4 flows down through a vertical passage 9 extending through the core 4 into the basin 3. Melt 6 is cooled by the cooling rolls 1 which rotates in directions indicated by the arrows so that a solidified shell 7 is formed and a casting 8 continuously leaves through the gap between the cooling rolls 1 out of the continuous casting machine.
In the dual-roll type continuous casting machine described above, melt 6 in the basin 3 is cooled by the cooling rolls 1, forming the solidified shell 7 over the cylindrical surfaces of the cooling rolls 1. In this case, the solidified shell 7 tends to grow at the so-called triple-point zones (i.e., zones of contact between the cooling rolls 1, the side dams 2 and melt 6) since melt 6 tends to tarry and thus tends to be sooner cooled at the triple- point zones. The solidified shell 7 which has grown upon the stationary side dams 2 is cooled, dropped therefrom by the rotating cooling rolls 1 and is crushed in the gap between the cooling rolls 1 so that there may arise the problems that the surface quality of the casting 8 is degraded; the thickness of the casting 8 is locally increased; the casting 8 is sheared; and the side dams 2 are damaged due to the drop of the solidifed shell 7 therefrom.
In order to solve the above and other problems, there has been devised and demonstrated a pouring device with an additional passage 12 as shown in FIG. 2. The passage 12 is opened at the surface of the core 4 in opposed relationship with the corresponding side dam 2 and extends through the core 4 so that part of the poured melt 6 is forced to flow through the passage 12 toward the so-called triple-point zones in the basin 3, thereby preventing the growth of the solidified shell 7 at the triple-point zones and especially at the side dams 2.
However, with the above-described pouring device, the flow rate of melt 6 flowing toward the side dam 2 is predeterminedly set so that any irregular and abnormal states of the solidified shell 7 growing at the triple-point zones cannot be compensated with, resulting in a problem that shapes of the widthwise edges of the casting 8 may be degraded due to any variations in casting conditions. The gap between the opposing surfaces of the core 4 and the side dam 2 may uncontrollably vary in response to variations in temperature of melt, resulting in variations in flow rate of melt 6 which can not be compensated with.
In view of the above, a primary object of the present invention is to provide a pouring device capable of varying the flow rate of melt to be supplied to the so-called triple-point zones in response to the growing conditions of the solidified shell and the unsteady state thereof.
The above and other objects, effects features and advantages of the present invention will become more apparent from the following description of some preferred embodiments thereof taken in conjunction with the accompanying drawings.